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Phenolic antioxidant free radical scavenging effect QSAR Studies

Author: SunYouMin
Tutor: ChenDeZhan；ZhangHongYu
School: Shandong Normal University
Course: Physical and chemical
Keywords: Phenolic antioxidants scavenge free radicals OH hydrogen abstraction reaction of the dissociation energy of QSAR
CLC: O641.1
Type: Master's thesis
Year: 2001
Downloads: 682
Quote: 2
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Abstract


Given the relationship between free radicals and disease very close and it is the oxidation of the food and chemical products, the main reason, therefore, to find efficient, non-toxic, inexpensive antioxidants have been widely expanded in different areas. Given the current most widely used phenolic antioxidants, so in-depth study of such antioxidant free radical scavenging mechanism, as well as on the basis of this mechanism summarizes QSAR antioxidants, antioxidants can deepen understanding and accelerate the screening of antioxidants . In this thesis, ab initio quantum chemistry methods and other physical and chemical methods calculated to characterize the antioxidant activity of the various theoretical parameters, and with mathematical statistics select the best correlation with experimental activity of a set of parameters to construct antioxidants QSAR . Further clarify the various structural factors on the theoretical parameters. The main results of this paper are: 1. Of phenolic antioxidants hydrogen abstraction reaction mechanism high level quantum chemical calculations, the transition state barrier, atomic net charges, dipole moments and other parameters, and comparison with the known experimental data clearly antioxidants hydrogen abstraction reactions mechanism. 2. Characterization Clear alkyl radicals, alkoxy radicals, alkyl peroxy radicals (R ·, RO ·, ROO ·) activity in the selection of physical-chemical parameters and calculation method using ab initio calculation of a series of static parameters of phenolic compounds including OH dissociation energy (BDE), OH bond lengths, bond orders, the charge difference, Mulliken electronic layout, vibrational force constants (k) and the highest occupied molecular orbital energy level (E HOMHO ) , and the calculated results with experimentally measured free radical scavenging rate constant logarithmic correlation analysis. The results showed: OH BDE is a good characterization of phenolic antioxidant free radical scavenging activity of theoretical parameters; E HOMHO can only characterize single phenolic compounds, containing more phenolic hydroxyl groups and the formation of intramolecular hydrogen key phenolic compounds is invalid; additional static parameters can not be measured phenolic antioxidant free radical scavenging activity. Due to the antioxidant water partition coefficient (logP) and phenolic hydroxyl hydrogen solvent accessibility (H-Surf) also have an impact on its activity, so the theory used in the paper indicators include: OH dissociation energies, logP and H -Surf and E HOMO . w ③ 3. Summary of QSAR using AM1 eight M z / ostrich [YP Tsai-3ZC (p ') method, and other physical and chemical methods calculate the 21 kinds of phenolic antioxidant agents physicochemical parameters, including referral {H 8 O * O 口 Pat India than the furnace *. 12; H-S22f, binding assay measured the inhibition of lipid peroxidation antioxidant efficiency * P%, by means of correlation analysis established antioxidant activity and the best correlation between the physical parameters of the relationship. Ie get Han AR. The equation is: [*% = 4,4 a / convex *. . +6, S? Xb shovel MLP a 717D73 Pat! 0M0 a Z, u3 Ah H a SLlff-N B u; Bu 0,9 into the beggar. Interpretation of the structure back hormone on Bu H dissociation energy of the structure back hormone mainly refers to substituents of phenolic antioxidants. Yu substituent on the 0-H dissociation energy of the impact of n arguments, including electronic effects and intramolecular hydrogen bonding effect. Pairs of single-substituted phenols. Phenoxyl radical stability

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CLC: > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Structural Chemistry > Chemical bond theory
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